Watts Conversion

The watt is a unit used to measure power. Use one of the conversion calculators below to convert to another unit of measure, or read on to learn more about watts.

Watt Conversion Calculators

Choose a unit of power to convert to.

SI Units
Convert watts to microwatts
1 watt is equal to 1,000,000 microwatts
Convert watts to milliwatts
1 watt is equal to 1,000 milliwatts
Convert watts to kilowatts
1 watt is equal to 0.001 kilowatts
Convert watts to megawatts
1 watt is equal to 1.0E-6 megawatts
US Customary & Imperial Units
Convert watts to mechanical horsepower
1 watt is equal to 0.001341 mechanical horsepower
Convert watts to electric horsepower
1 watt is equal to 0.00134 electric horsepower
Convert watts to btu per hour
1 watt is equal to 3.412142 btu per hour
Other Units
Convert watts to kilocalories per hour
1 watt is equal to 0.860421 kilocalories per hour
Related Calculators
Convert watts to amperes
1 watt at 120 volts is equal to .008333 amps
Convert watts to joules
1 watt over 60 seconds is equal to 60 joules
Convert watts to kilovolt-amperes
1 watt with a power factor of .8 is equal to .00125 kilovolt-amps
Convert watts to kilowatt-hours
1 watt over 24 hours is equal to .024 kilowatt-hours
Convert watts to volts
1 watt at 12 amps is equal to .0833 volts

Watt Definition and Usage

One watt is the power equal to the rate of energy of one joule per second in an electrical circuit. One watt is also equal to the power produced in a circuit with a voltage potential of one volt with a current of one amp.

The watt is the SI derived unit for power in the metric system. Watts can be abbreviated as W, for example 1 watt can be written as 1 W.

Watt's Law states the relationship between power, current, and voltage. Using Watt's Law, it's possible to express the power in watts as an expression using current and voltage.

PW = IA × VV

The power in watts is equal to the current in amperes times the potential difference in volts.

Combining this with Ohm's Law, it's also possible to express the power in watts using resistance in addition to volts and amps.

Background and Origin

The watt is named after James Watt, a Scottish inventor who created the steam engine. The watt was proposed as a unit in 1882 by C. William Siemens, and formally adopted as the "international watt" in 1908 at the International Conference on Electric Units and Standards. In 1948 the watt was redefined to be based on absolute units rather than practical units, and is the definition of the unit we use today.

Watts Measurement Conversion Table

Watts and the equivalent power measurements
watts microwatts milliwatts kilowatts megawatts mechanical horsepower electric horsepower btu per hour kilocalories per hour
1 W 1,000,000 µW 1,000 mW 0.001 kW 0.000001 MW 0.001341 hp(I) 0.00134 hp(E) 3.412142 Btu/h 0.860421 kcal/h
2 W 2,000,000 µW 2,000 mW 0.002 kW 0.000002 MW 0.002682 hp(I) 0.002681 hp(E) 6.824285 Btu/h 1.720842 kcal/h
3 W 3,000,000 µW 3,000 mW 0.003 kW 0.000003 MW 0.004023 hp(I) 0.004021 hp(E) 10.236427 Btu/h 2.581262 kcal/h
4 W 4,000,000 µW 4,000 mW 0.004 kW 0.000004 MW 0.005364 hp(I) 0.005362 hp(E) 13.64857 Btu/h 3.441683 kcal/h
5 W 5,000,000 µW 5,000 mW 0.005 kW 0.000005 MW 0.006705 hp(I) 0.006702 hp(E) 17.060712 Btu/h 4.302104 kcal/h
6 W 6,000,000 µW 6,000 mW 0.006 kW 0.000006 MW 0.008046 hp(I) 0.008043 hp(E) 20.472855 Btu/h 5.162525 kcal/h
7 W 7,000,000 µW 7,000 mW 0.007 kW 0.000007 MW 0.009387 hp(I) 0.009383 hp(E) 23.884997 Btu/h 6.022946 kcal/h
8 W 8,000,000 µW 8,000 mW 0.008 kW 0.000008 MW 0.010728 hp(I) 0.010724 hp(E) 27.29714 Btu/h 6.883367 kcal/h
9 W 9,000,000 µW 9,000 mW 0.009 kW 0.000009 MW 0.012069 hp(I) 0.012064 hp(E) 30.709282 Btu/h 7.743787 kcal/h
10 W 10,000,000 µW 10,000 mW 0.01 kW 0.00001 MW 0.01341 hp(I) 0.013405 hp(E) 34.121425 Btu/h 8.604208 kcal/h
11 W 11,000,000 µW 11,000 mW 0.011 kW 0.000011 MW 0.014751 hp(I) 0.014745 hp(E) 37.533567 Btu/h 9.464629 kcal/h
12 W 12,000,000 µW 12,000 mW 0.012 kW 0.000012 MW 0.016092 hp(I) 0.016086 hp(E) 40.945709 Btu/h 10.32505 kcal/h
13 W 13,000,000 µW 13,000 mW 0.013 kW 0.000013 MW 0.017433 hp(I) 0.017426 hp(E) 44.357852 Btu/h 11.185471 kcal/h
14 W 14,000,000 µW 14,000 mW 0.014 kW 0.000014 MW 0.018774 hp(I) 0.018767 hp(E) 47.769994 Btu/h 12.045891 kcal/h
15 W 15,000,000 µW 15,000 mW 0.015 kW 0.000015 MW 0.020115 hp(I) 0.020107 hp(E) 51.182137 Btu/h 12.906312 kcal/h
16 W 16,000,000 µW 16,000 mW 0.016 kW 0.000016 MW 0.021456 hp(I) 0.021448 hp(E) 54.594279 Btu/h 13.766733 kcal/h
17 W 17,000,000 µW 17,000 mW 0.017 kW 0.000017 MW 0.022797 hp(I) 0.022788 hp(E) 58.006422 Btu/h 14.627154 kcal/h
18 W 18,000,000 µW 18,000 mW 0.018 kW 0.000018 MW 0.024138 hp(I) 0.024129 hp(E) 61.418564 Btu/h 15.487575 kcal/h
19 W 19,000,000 µW 19,000 mW 0.019 kW 0.000019 MW 0.025479 hp(I) 0.025469 hp(E) 64.830707 Btu/h 16.347995 kcal/h
20 W 20,000,000 µW 20,000 mW 0.02 kW 0.00002 MW 0.02682 hp(I) 0.02681 hp(E) 68.242849 Btu/h 17.208416 kcal/h

You might also find our other electrical calculators useful.